minimizes bypassing. However when this results in excessive velocities entering the shell, then it is recommended that some tubes near the inlet nozzle be removed or a dome or distributor belt be installed.
（b）If you choose the option to remove tubes within the nozzle projection, the program will eliminate any tubes, which would extend beyond the lowest part of the nozzle cylinder. In many cases, using this option will have no effect since nozzles, which are relatively small in comparison to the shell diameter (say smaller than 1/4 the shell diameter) will not extend to the first row of tubes anyway.
（c）A nozzle dome with a full layout reduces the velocity entering the shell, but does not effect the velocity entering the bundle.
（d）A distributor belt with a full layout is the most effective way to reduce entrance velocities, but it is usually the most expensive.
（e）When you remove tubes so that the shell entrance area equals the inlet nozzle area, the tube layout is the same as when installing an impingement plate on the bundle, although the presence of the impingement plate is determined by another input item described next. This is usually a very effective way of decreasing entrance velocities.
Default: normal with full layout if no impingement plate; nozzle dome with full layout if impingement plate in nozzle dome; remove tubes so that shell entrance area equals inlet nozzle area if impingement plate on bundle
Shell exit construction壳体出口结构
（2）Provide disengagement space in shell (pool boilers only) 提供气体空间（只对锅炉使用）
如果选定该项，则为了给产生的蒸汽提供足够的空间，将会使壳体直径增加。如果对釜式壳体选定该项，程序将提供足够的空间。
If specified, the shell diameter will be increased to provide disengagement space for the vapor generated. If a kettle shell is specified, the program will always provide the disengagement space.
（3）Percent of shell diameter for disengagement 指定空间相对于壳体直径的百分比 您可以指定使产生的蒸汽提供足够的空间的百分比
You can specify the percentage of disengagement space needed. （4）Impingement（壳体入口设置防冲板或导流板） （a）壳程设置防冲板或导流板的条件
①?? 对无腐蚀的、不易结垢的单一流体而言，当通过接管的Rho * V2超过2232 kg/(m*s2)
或1500 lb/(ft*s2)时； ②?? 对腐蚀性的、易结垢的流体而言，当通过接管的Rho * V2超过744 kg/(m*s2)或
500lb/(ft*s2)时；
③当被认为是饱和蒸气时； ④对腐蚀性气体 ⑤当为两相流时
（b）Impingement protection type防冲挡板及导流板类型
如果你选择了“防冲板（plate）”，程序将会自动删除入口接管下的换热管，并且使得壳体入口面积等于接管下横截面积。这相当于在接管中心下（即接管直径的1/4的范围内）拆除了换热管，这目的是精确计算“束缚入口流速”。程序默认防冲板为圆形（circular）的，无齿孔（unperforated）的，其尺寸为接管的内直径，约3mm或1 / 8in厚。 还有一种情况是将安装防冲挡板的接管扩径（dome），其扩径形式有圆柱或圆锥两种，多为圆柱。
这两种类型都有自己的优点和缺点。如果只是安装一个防冲挡板，它将会分散流体，其既不会导致扩径的高昂费用，也不会出现开孔的困难（对蒸汽入口往往要做这个工作）。然而，如果拆除入口换热管，将会导致壳体、管板、法兰直径增大等。特别是，当合金制造的管板或壳体及物流入口接管等不能增大时，带有扩径的防冲挡板算是较便宜的。
还有一种情况，需安装导流板，这种板带有孔，这种孔有利于减少流速。但是孔流会导致接管局部腐蚀。
默认值：对蒸汽冷凝或液体汽化默认为圆形防冲挡板（circular plate），其他情况则没有防冲挡板。
The purpose of impingement protection is to protect the tubes directly under the inlet nozzle by deflecting the bullet shaped flow of high velocity fluids or the force of entrained droplets. TEMA recommends that inlet impingement protection be installed under the following conditions:
①When the rho*V2 through the inlet nozzle exceeds 2232 kg/(m*s2) or 1500 lb/(ft*s2) for non-corrosive, non-abrasive, single phase fluids
②When the rho*V2 through the inlet nozzle exceeds 744 kg/(m*s2) or 500 lb/(ft*s2) for corrosive or abrasive liquids
③When there is a nominally saturated vapor ④When there is a corrosive gas
⑤When there is two phase flow at the inlet
If you choose a plate on the bundle the program will automatically remove tubes under the inlet nozzle so that the shell entrance area equals the cross-sectional area of the nozzle. This is approximately equal to removing any tubes within a distance of 1/4 the nozzle diameter under the center of the nozzle. For purposes of calculating the bundle entrance velocity, the program defaults to an impingement plate that is circular, unperforated, equal in diameter to the inside diameter of the nozzle, and approximately 3 mm or 1/8 in. thick.
An alternative is to put a plate in a nozzle dome, which means suspending the impingement plate in an enlarged nozzle neck, which may be a dome or a cone.
Both types have their advantages and disadvantages. If the plate is on the bundle, the flow is more widely distributed, and there is neither the expense for the enlarged nozzle neck nor the increased potential of fabrication problems when cutting a large hole in the shell (as can often happen with vapor inlet nozzles). However, since tubes are removed, it may require larger diameter shell, tubesheets, flanges, etc. Especially in cases where the tubesheets and/or shell are made of alloy and the inlet nozzle is not large, the impingement plate in the nozzle dome may be significantly less expensive.
For some special applications, the plate may be perforated. The primary advantage being that the perforations will help reduce the velocity into the bundle. The main concern with perforated plates is that flow through the holes could cause localized erosion for certain tube materials.
Default: circular plate on bundle if condensation or vaporization is occurring on the shell side; none otherwise
（d）Impingement plate diameter防冲板直径
程序将依据输入参数，确定防冲板的直径与位置。如果已经指定了物流入口接管的外径，就没有必要指定该尺寸。
默认值为物流入口接管的外径。
The program will use this input to determine the position and the dimension of the
impingement plate. This input is not required if you have already specified the shell inlet nozzle OD.
The default is the shell inlet nozzle O.D.
（e）Impingement plate length and width防冲挡板的长度和宽度
你可以指定矩形防冲挡板的尺寸。
将物流入口接管的外径默认为矩形防冲挡板的长与宽。 You can specify a rectangular impingement plate size.
The default is the shell inlet nozzle O.D. for length and width (square plate).
（f）Impingement plate thickness防冲挡板的厚度
如果要设置防冲挡板，这个尺寸是必须的。你可以指定任意的厚度。默认值为3mm或0.125inch。
This input is required if you specify there is an impingement field. You can specify any thickness for the impingement plate. The default is 3 mm or 0.125 inch.
（g）Impingement distance from shell ID壳体内侧到防冲挡板的距离
您可以指定从壳体内侧到防冲挡板的距离。默认为最顶层换热管所在的位置。 You can specify the distance from the shell inside diameter to the impingement plate. The default is the top row of tubes.
（h）Impingement clearance to tube edge防冲挡板到第一排换热管的距离
您可以指定从防冲挡板到第一行换热管的距离。
You can specify the distance from the impingement plate to the first row of tubes.
（i）Impingement plate perforation area %导流板穿孔面积百分数
如果您使用的是多孔型导流板，您可以指定穿孔的面积百分数。
If you are using a perforated type impingement plate, you can specify the percent of area that the plate is perforated.
（3） Layout Options布置 （a）Pass layout布置
管程有四程或更多。这将影响热计算，并影响管数。
四分之一布局（Quadrant layout）通常（但并不总是）布置的换热管最多。通常用于四程或更多程的U型管换热器。接管侧的换热管必须要偏移中心线。对于安装纵向折流板的6,10，或14程换热器避免使用该布置，这是为了防止短路。
混合布局（Mixed）有利于使接管侧换热管布置在中心线上。管子数接近或超过四分之一布
局。对安装纵向折流板的4,8，12，或16管程的换热器避免使用该布置。
带状布局（Ribbon）布置的管数比前两种都少，其管程数常为奇数。也可用于X-type换热器。带状布局的主要优点是从上到下的管板在相邻的管工作温度的逐渐变化的。这可以是特别重要的，在管侧气温变化很大，这可能会导致显着的热应力，特别是混合象限布局。 默认值：程序优化
There are several possible ways to layout tubes for four or more passes. The primary effect on the thermal design is due to the different number of tubes, which are possible for each type.
Quadrant layout has the advantage of usually (but certainly not always) giving the highest tube count. It is the required layout for all U-tube designs of four or more passes. The tube side nozzles must be offset from the centerline when using quadrant layout. The program will automatically avoid quadrant layout for shells with longitudinal baffles and 6, 10, or 14 pass, in order to avoid having the longitudinal baffle bisect a pass.
Mixed layout has the advantage of keeping the tube side nozzles on the centerline. It often gives a tube count close to quadrant and sometimes exceeds it. The program will automatically avoid mixed layout for shells with longitudinal baffles and 4, 8, 12, or 16 passes.
Ribbon layout nearly always gives a layout with fewer tubes than quadrant or mixed layout. It is the layout the program always uses for an odd number of tube passes. It is also the layout preferred by the program for X-type shells. The primary advantage of ribbon layout is the more gradual change in operating temperature of adjacent tubes from top to bottom of the tubesheet. This can be especially important when there is a large change in temperature on the tube side, which might cause significant thermal stresses in mixed and especially quadrant layouts. Default: program will optimize
（b）Design symmetrical tube layout对称布管选项
选择了此项，程序将换热管上下对称布置。
Program will make the tube pattern as symmetrical as possible for the top to bottom.
（c）Maximum % deviation in tubes per pass每程管子的最大偏差
该输入值可确定每程管数可接受的偏差值。在管板布置中，该值用来确定最大的换热管数。
理想情况下，它是理想的在每个通管相同数量的时候没有变化 在管侧相。然而，对于超过两大部分的布局，这将 需要删除管，否则将外管内。因为它是
比表面积最大化在一个给定的外壳和减少可能的壳 侧旁路管，每通过一个合理的偏差通常是可以接受的。 建议您不要因为这给了显着不同的大偏差 在一些通过速度和过多地增加额外的压力降 膨胀和收缩损失。自从杨hetran程序库管侧
对管每通过一个平均数计算，这种畸变没有反映在 热设计。 默认值：5%